Discovery Communications Headquarters

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Discovery Communications
Headquarters
Silver Springs, MD
Josh Woolcock Structural Option
Architectural Engineering Pennsylvania State
University
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Outline

• Building Information
• Existing Conditions
• Structural Analysis
• Cost Analysis
• Schedule Analysis
• Office Lighting Design
• Conclusions

Pennsylvania State University Architectural
Engineering
Josh Woolcock Structural Option
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Project Team
Owner Discovery Communications Inc.
Architect SmithGroup Inc.
General Contractor Clark Construction
Engineers Structural KTLH Engineering
Civil VIKA Inc. MEP Flack Kurtz
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Engineering
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Building Overview
Layout Function
- Multipurpose Office Facility - two independent
towers, of 7 and 10-stories - 3 levels of
underground parking - 550,000 sqft. of open
office space - 52 Million overall cost
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Engineering
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Existing ConditionsMechanical

• Individual air-handling units on each floor
• Duct work for tenant build-out
• - 3 centrifugal water chillers and roof cooling
  towers
• - 3 gas-fired furnaces

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Engineering
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Existing ConditionsLighting / Electrical
- Three 4,000A three-phase feeders for three
switchboards, totaling 12,000A - Lighting in
office space reserved for tenant build-out
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Existing ConditionsStructural

• - CIP Concrete Structural System
• - Two structurally independent towers
• - 2-way cambered 9 structural slab with drop
  panels
• 30 x 30 column grid
• Column sizes up to 36 x 48

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Engineering
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Structural Analysis
Focus North Tower 10 Office Floors Penthouse
Purpose To reduce the size of the columns within
the office spaces to reduce concrete volume,
increase floor space and promote aesthetics.
Reasons for Initial Size - Act as both lateral
and gravity system - Building sway constraints -
Large dead Loads
Possible Solutions - Separation of Lateral and
Gravity Systems - Reduction of Gravity Loads
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Engineering
Josh Woolcock Structural Option
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Structural AnalysisInitial Considerations

• Loads calculated from IBC2000
• Deflection Requirements
• H/400 for service wind loads
• H/50 for service seismic loads
• Respect to other tower Contact at 8th Floor
• Building Geometry
• Much longer than it is wide
• -Secondary Considerations
• -Building Floor Plan and Impact
• Impact on other building systems

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Engineering
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Structural AnalysisFloor Slab Reduction

• ADOSS was used Equivalent Frame Method
• Floor slab construction switched from 4000psi to
  5000psi concrete
• Slab thickness reduced from 9 to 8
• Drop panels remain 7.5
• Slab Reinforcement increased from an average of
  4.46psf to 4.89psf
• Maximum DL deflection is 0.759
• Slab weight was reduced by 11 or 11.25kip per
  column per floor

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Engineering
Josh Woolcock Structural Option
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Structural AnalysisShear Walls

• 4 preliminary locations for shear walls
• Locations do no hinder original floor plan
• Tests were performed to determine their lateral
  performance
• Use of 4 walls resulted in excess torsion
• 2 shear walls were implemented and located to
  reduce torsion in building

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Engineering
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Structural AnalysisShear Wall Design

• Walls Start at floor 1 and continue to main roof
• Walls span column-to-column
• Design changes at floors 1,3,5 7
• Maximum loads Wind w/ Torsion Factored
• 765.3 kip Shear
• 57269.81ft-kip Bending
• 1909 kip Axial

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Engineering
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Structural AnalysisShear Wall Design

• 24 x 36 columns at ends
• Concrete strength
• 10000psi at Floor 1
• 8000psi at Floor 3
• 4000psi at floor 5
• Wall Reinforcement
• 5_at_18 Horz.
• 5_at_18 Vert.

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Engineering
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Structural AnalysisShear Transfer

• Shear Walls stop at first floor
• Columns continue down to foundation
• No Bending in Slab
• - Shear transferred from walls to floor slab then
  to retaining walls
• - Lateral earth pressure resists shear and locks
  floor 1 in place

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Engineering
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Structural AnalysisColumn Reduction

• All Columns within office spaces are 24 x 24
• 4 different column designs
• Concrete Strengths
• 8000psi Floor 1
• 6000psi Floor 3
• 4000psi Floor 5
• 4000psi Floor 7

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Engineering
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Structural AnalysisFinal Lateral System

• North-South Direction
• Combination of Shear walls and Moment Frames
• Contribution via stiffness analysis
• 66.8 Shear walls at floor 10
• 90.1 Shear walls at floor 5
• 96.3 Shear walls at Floor 1
• East-West Direction
• Moment Frames

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Engineering
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Structural AnalysisLateral System Performance

• North-South Direction

Notes Max Wind 2.66 Max Seismic 2.54

• East-West Direction

Notes Max Wind 2.32 Max Seismic 4.44
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Engineering
Josh Woolcock Structural Option
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Structural AnalysisConclusions

• Reduction in floor slab produced a 11 decrease
  in slab dead load on columns
• Implementation of Shear Walls reduced bending
  stresses in columns due to lateral forces
• Column size was reduced to 24x24 throughout the
  office spaces
• - Placement of Shear Walls did not adversely
  affect building floor plan or mechanical and fire
  protection services

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Engineering
Josh Woolcock Structural Option
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Cost AnalysisInitial Considerations
Purpose Determine cost implications of new
structural systems
- Detailed Estimate performed on both original
and new structural systems - Costs Estimated
using RSMeans 2001 - Bare Costs Overhead and
Profit not included
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Engineering
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Cost AnalysisColumns
Notes - 43.8 Reduction in volume (1210cy) -
25 Reduction in formwork (28000sqft) - 14.3
increase in reinforcement - Cost Savings of
157,017.74
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Engineering
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Cost AnalysisFloor Slab
Notes - 1 reduction in slab thickness - 11.1
Reduction in volume (1260cy) - 7.2 increase in
reinforcement - Increased Cost of 5,493.33
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Engineering
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Cost AnalysisShear Walls

• Notes
• 291.33cy of additional concrete
• 14,683.2 sqft of formwork
• 12.6 ton of additional reinforcement
• Approximately 81,700 in additional cost

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Engineering
Josh Woolcock Structural Option
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Cost AnalysisConclusions

• Notes
• 2178.67 cy reduction in concrete
• 14,366 sqft reduction in formwork
• 106.66 ton increase in reinforcement
• Cost savings of nearly 70,000.00

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Engineering
Josh Woolcock Structural Option
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Schedule AnalysisInitial Considerations
Purpose Analyze construction time and
sequencing of new structural system via floor to
floor erection time

• Possible construction sequence for the original
  and new system
• Based on a 2 week floor to floor construction
  time
• Production number calculated from 2001 edition of
  RSMeans
• Slab pours would be made every 2 days to
  facilitate construction of both towers
  simultaneously

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Engineering
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Schedule AnalysisProduction

• Production capacity
• 1 crew can erect 3 columns / day
• 1 crew can erect 1 shear wall / 2 days

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Engineering
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Schedule AnalysisOriginal System

• 70 Columns in 10 days
• 2.3 crews needed

• Columns
• 2 Form crews
• 1 Rebar crew
• 1 Concrete crew

• Elevated Slab
• 4 Form Crews
• 3 Rebar Crews
• 2 Concrete Crews

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Engineering
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Schedule AnalysisNew System

• 70 Columns 2 Shear Walls in 10 days
• Equivalent to 82 Columns
• 2.73 crews needed

• Columns / Shear Wall
• 3 Form crews
• 1 Rebar crew
• 1 Concrete crew

• Elevated Slab
• 4 Form Crews
• 3 Rebar Crews
• 2 Concrete Crews

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Engineering
Josh Woolcock Structural Option
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Schedule AnalysisConclusions

• Both systems require same crews for elevated slab
  work
• New structural system requires 1 additional crew
  for columns / shear walls

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Engineering
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Office LightingInitial Considerations
Purpose Design a general lighting system for
the open office spaces

• Ceiling height is approximately 11-8
• No finished ceiling
• Exposed underside of concrete slab
• Exposed Mechanical 18 Deep
• Spaces used primarily used for office work
• Requires Approximately 50fc or 500lx on the work
  plane
• Best choice for these requirements is an indirect
  lighting system

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Engineering
Josh Woolcock Structural Option
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Office LightingDesign

• Due to exposed mechanical systems and no finished
  ceiling, indirect lighting would not work well
• Decision to incorporate reflector panels was made
• Provide ideal surface for reflected light
• Hang 24 from ceiling
• Able to provide access to exposed mechanical and
  fire protection services

Pennsylvania State University Architectural
Engineering
Josh Woolcock Structural Option
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Office LightingResults

• Model was created using Lightscape
• Peerless LDX030452 was selected
• Uses (3) 32W T8 lamps
• Input Wattage of 113W
• Produced approximately 510lx on work plane
• Power density of 0.715 W/sqft

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Engineering
Josh Woolcock Structural Option
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Office LightingRenderings
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Conclusions Recommendations

• Floor slabs were reduced from 9 to 8 resulting
  in an 11 reduction in dead load
• Implementation of shear walls reduced bending
  stresses in columns
• Column size reduced to 24x24
• 43.8 reduction in volume
• 2200 sqft of additional floor space
• New design results in a savings of 70,000
• No change in floor cycle time
• Lighting design provides an efficient and
  aesthetic pleasing system for the general office
  spaces

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Engineering
Josh Woolcock Structural Option
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Acknowledgements
Thank You to the following. - Discovery
Communications Inc. - Clark Construction Inc.
with special consideration to Ray
Sowers George Conard Ken Alexander - The
entire AE Faculty with special consideration
to Dr. Lewis Geschwindner Dr. Thomas
Boothby Dr. Linda Hanagan - My Family - My
Friends in and out of Architectural Engineering
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Engineering
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Questions
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Location

• Silver Springs, MD
• Intersections of Georgia Avenue and Colesville
  Road
• Approximately 8 miles from downtown Washington
  D.C.

Pennsylvania State University Architectural
Engineering
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Building Overview
Layout Function
- Multipurpose Office Facility - two independent
towers, of 7 and 10-stories - 3 levels of
underground parking - 550,000 sqft. of open
office space - 52 Million overall cost
Architecture
- Aluminum and Glass curtain wall
system -12-story glass atrium connects the two
building - Rooftop Terrace and Garden
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Engineering
Josh Woolcock Structural Option
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Structural AnalysisShear Walls

• No impact on existing mechanical and Fire
  Protection Services

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Engineering
Josh Woolcock Structural Option
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Structural Analysis3D Analysis
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Engineering
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Breadth Aspects
Lateral System Cost Analysis Determine cost
implications of new structural systems
Lateral System Schedule Analysis Analyze
construction time and sequencing of new
structural system via floor to floor erection time
Office Lighting Design Design a general
lighting system for the open office spaces
Pennsylvania State University Architectural
Engineering
Josh Woolcock Structural Option